Technical Field
The present disclosure relates to the field of digital communication and, more specifically, to acknowledgement transmitted between two nodes in communication.
Description of Related Art
Modern communication systems designed for operation on power line and other mediums, which tend to suffer from dynamically changing channel and noise conditions, include retransmission mechanisms at the physical layer to improve the throughput for the user. One such communication standard is the ITU-T G.hn family of standards.
The ITU-T G.hn family of standards (G.9960, G.9961 and G.9963, for example, at: http://www.itu.int/ITU-T/recommendations/index.aspx?ser=G) includes an acknowledgement mechanism whereby a source node can request a destination node to send an immediate acknowledgement after the destination node completes receiving the frame transmitted by the source node. The acknowledgement consists of a limited number of bits which can be used to communicate the status of the received data units to the transmitter, the source node, in order for the transmitter to retransmit the data units that are indicated by the receiver as received with error. The mechanism also allows several compression schemes in order to ensure that the limited number of bits available in the acknowledgement frame are sufficient to communicate the status of the received data units in most practical cases. In some cases the compression results in unnecessary retransmission of data units that have been received correctly by the destination node for which the status could not be communicated due to lack of sufficient number of bits in the acknowledgement frame.
However, the new G.9963 standard (multiple-input-multiple-output, or MIMO, version of G.hn) significantly exacerbates the issue of limited number of bits in the acknowledgement frame because the data transmission capability is approximately doubled under the G.9963 standard compared to single-input-single-output, or SISO (G.9960/G.9961), and may result in a lot of unnecessary retransmissions that would reduce the overall data transmission efficiency as well as increase the time on wire and power consumption. The maximum allowed transmission window size for the acknowledgement mechanism was also increased for both G.9961 and G.9963 standards to address the requirements of high throughput links. This further exacerbates the issue of limited number of bits in the acknowledgement frame.